A mold clamping unit of this type is known from EP 0 658 136 B1 wherein a liquid-cooled servo motor is used to achieve a higher energy yield as a drive motor for a symmetrical force transmission to a toggle mechanism as well as for an energy-saving operation. Using the water as a cooling medium, heat given off by the electric servo motor can be recovered as energy and then used for tool tempering for example. The servo motor drives a rotationally-fixed spindle such that a favourable mechanical system is obtained.
A clamping unit for an injection molding machine in which a lubricant supply is provided to supply lubricant both to the joints of a toggle and to a spindle drive with spindle and spindle nut is known from DE 10 2004 042 744 A1.